The object whose class chain is inspected. A non-object returns false.
The property name to look for.
The class declaring the default implementation. A member BaseClassRef does
not itself declare returns false — there is no baseline to have overridden.
True when some class below BaseClassRef declares member.
Determines whether a subclass has replaced
membersomewhere betweeninstanceandBaseClassRef.Distinguishes "the author made no choice" from "the author chose the value that happens to be the default" — something a getter cannot express on its own. A base class member returning
truelooks identical whether a subclass deliberately opted in or never knew the member existed, so an API whose default sits in the off position silently disables the subclasses that most wanted it on. Asking whether the member was overridden recovers the intent.Handles methods and accessors alike by comparing property descriptors, and finds an override declared anywhere in a multi-level chain — a generated class, an application subclass, a server-side subclass layered on top of it.